A Stirling Engine is what rumour had the original Segway billed as. They are incredibly quiet, efficient machines powered by gas expanding as it heats up, and compressing as it cools down. The heat could come from anything from the sun to decomposing compost. In the SFA Stirling Engine Project, the heat comes from a tea light. It's a great little project for illustrating how common household objects could be repurposed into actual power sources, with a little imagination and elbow grease. [GT]
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From: BEST OF 2008: Eco-friendy and sustainable shoes